The pair finished fourth in their heat on Day 1 of the regatta with a performance well below their normal high standards, but the heroes of Beijing began working their way back into form with a solid victory.

Brennan and Crawshay forged an early lead over Ukraine and Canada and by the 1000m mark had clear water on the field.

The margin had pushed out to more than six seconds with 500m remaining and stroked by Tasmanian Brennan, who revealed his Olympic campaign was almost over three weeks ago, the pair crossed the line in a time of 6:25.36 to book their place in the semi-finals.

"Today was really what we should have done yesterday," Crawshay said. "Just in terms of the way we went about it off the start we just had a bit more push through the stroke and it set the race up well.

"After 20 strokes we knew it was going to be a good one and that is not what we had yesterday,"

The gold medal winning duo will face a tough semi-final draw on Day 4 (Tuesday 31 July) but remains confident of progressing through to the final that will be held two days later.

Australia's self-titled Motley Crew also made their bow at the Olympic regatta and faced women's eight world and Olympic champions USA, as well as home town favourites GB and Germany.

Coxed by Beijing Olympian Lizzy Patrick the crew, featuring Phoebe Stanley, Sally Kehoe, Alex Hagan, Tess Gerrand, Sarah Cook, Robyn Selby Smith, Renee Chatterton and Hannah Vermeersch, started well behind the United States and were second through the first two time checks.

Great Britain mounted a challenge to Australia nearing the 1500m mark, but the Australian crew showed experience beyond their years to withstand the challenge and power away, crossing the line second behind USA in a time of 6:20.89.

They will now row a repechage on Tuesday against Great Britain, Germany, Romania and the Netherlands, with four crews progressing to the A Final.

Hannah Every-Hall and Bronwen Watson made their Olympic debut in style with a superb second place finish behind current world champions Greece.

In a heat of the lightweight women's double scull that featured four finalists from the 2011 world championships, Watson and Every-Hall did not let the Greeks get away and crossed the line less than a boat length behind.

Watson, 35, and Every-Hall, 34, progress to the semi-final on Day 4 of competition and the latter said it was an important step.

"The Greeks were extremely dominant last year and are a crew to respect," Every-Hall, the mother of two said.

"We've had a few obstacles through the first two world cups this year but we have always known what we are capable of."

Tom Gibson and Rod Chisholm faced a tough heat in the lightweight men's double scull against the current Olympic champions from Great Britain and the reigning world champions Storm Uru and Peter Taylor of New Zealand.

Gibson and Chisholm, who earned their Olympic berths with second place at the Final Olympic Qualification Regatta in Lucerne, Switzerland in May, produced a solid opening 1000m to position themselves third and they held this to finish behind Great Britain and New Zealand.

The Australian men's four and women's double scull will contest their heats in Day 3 (Monday 30 July) action, while the women's quad scull and men's eight race a repechage in their bid to make the final.